Django 中的多字段外键

Question

我在 Django 中有两个模型，定义如下。创意状态模型：

class RtbdCreativeStatus(models.Model):
    creative_id = models.CharField(max_length=500, primary_key=True)
    advertiser_id = models.CharField(max_length=100, primary_key=True)
    exposure_level = models.CharField(max_length=125)
    modified_on = models.DateTimeField()
    modified_by = models.CharField(max_length=100)


class RtbdCreative(models.Model):
    id = models.AutoField(primary_key=True)
    advertiser_id = models.ForeignKey(RtbdCreativeStatus, on_delete=models.CASCADE)
    creative_id = models.ForeignKey(RtbdCreativeStatus, on_delete=models.CASCADE)
    country_id = models.IntegerField()
    adm = models.CharField(max_length=255, null=True, blank=True)
    sample_url = models.CharField(max_length=500)
    landing_page = models.CharField(max_length=500, null=True, blank=True)
    html = models.CharField(max_length=500)
    creative_attributes = models.CommaSeparatedIntegerField(max_length=150, null=True, blank=True)
    advertiser_domains = models.CharField(max_length=500)
    description = models.CharField(max_length=500, null=True, blank=True)
    created_on = models.DateTimeField(auto_now=True, auto_now_add=True)
    creative_type = models.CharField(max_length=50, null=True, blank=True)
    demand_source_type_id = models.IntegerField()
    revalidate = models.BooleanField(default=False)

(creative_id,adverter_id) 组合在我的 CreativeStatus 表中是唯一的。我希望该组合成为我的 Creative 表的外键。我尝试添加它，但出现此错误。

1）我如何使用两个组合键作为我的外键来实现这种连接。

2）从 CreativeStatus 表中获取所有广告及其状态的查询应该是什么。

更新 1

在阅读下面的答案时，我更新了我的模型，如下所述：

class RtbdCreative(models.Model):
    id = models.AutoField(primary_key=True)
    advertiser_id = models.ForeignKey(RtbdCreativeStatus, to_field='advertiser_id', related_name='advertiser', db_column='advertiser_id', on_delete=models.CASCADE)
    creative_id = models.ForeignKey(RtbdCreativeStatus, to_field='creative_id', related_name='creative', db_column='creative_id', on_delete=models.CASCADE)
    country_id = models.IntegerField()
    adm = models.CharField(max_length=255, null=True, blank=True)
    sample_url = models.CharField(max_length=500)
    landing_page = models.CharField(max_length=500, null=True, blank=True)
    html = models.CharField(max_length=500)
    creative_attributes = models.CommaSeparatedIntegerField(max_length=150, null=True, blank=True)
    advertiser_domains = models.CharField(max_length=500)
    description = models.CharField(max_length=500, null=True, blank=True)
    created_on = models.DateTimeField(auto_now=True, auto_now_add=True)
    creative_type = models.CharField(max_length=50, null=True, blank=True)
    demand_source_type_id = models.IntegerField()
    revalidate = models.BooleanField(default=False)

现在我收到这个错误. 我将 adser_id 、 craetive_id 组合为 unique 。但是 django 期望两者都是独一无二的。我该怎么做才能让它发挥作用？

Answer 1

正如 ERRROS 中提到的，当您想为同一模型添加多个外键时，您需要添加 related_name 作为参数。

class Creative(models.Model):
    id = models.AutoField(primary_key=True)
    advertiser_id = models.ForeignKey(RtbdCreativeStatus,
                                      related_name="Advertiser", on_delete=models.CASCADE)
    creative_id = models.ForeignKey(RtbdCreativeStatus,
                                    related_name="Creative",
                                    on_delete=models.CASCADE)
    country_id = models.IntegerField()
    adm = models.CharField(max_length=255, null=True, blank=True)
    sample_url = models.CharField(max_length=500)
    landing_page = models.CharField(max_length=500, null=True, blank=True)
    html = models.CharField(max_length=500)
    creative_attributes = models.CommaSeparatedIntegerField(
        max_length=150, null=True, blank=True)
    advertiser_domains = models.CharField(max_length=500)
    description = models.CharField(max_length=500, null=True, blank=True)
    created_on = models.DateTimeField(auto_now=True, auto_now_add=True)
    creative_type = models.CharField(max_length=50, null=True, blank=True)
    demand_source_type_id = models.IntegerField()
    revalidate = models.BooleanField(default=False)